For the photoconductive material to constitute the light receiving layer of an electrophotographic light receiving member, it is required to be highly sensitive to light, exhibits a high S/N ratio [photocurrent (Ip)/darkcurrent (Id)], has absorption spectral characteristics compatible with the spectral characteristics of magnetic waves irradiated, has a quick responsiveness to light and has a desirable dark electric resistivity. Other than these, it is also required for said material to be not harmful to the human body.
As the material to meet the above requirements, there is known an amorphous silicon material (hereinafter referred to as "a--si). There have been proposed various electro-photographic light receiving members respectively having a light receiving layer composed of "a--si.
Shown in FIG. 2 is a typical constitution of such electrophotographic light receiving member which comprises a substrate 201 and a light receiving layer 202 disposed on said substrate, said light receiving layer being formed of "a--si. This electrophotographic light receiving member is prepared by forming a film comprising "a--si to be the light receiving layer 202 on the substrate 201 in accordance with a relevant film-forming method such as thermal-induced CVD method, plasma CVD method or sputtering method.
The known electrophotographic light receiving members respectively having a light receiving layer composed of "a--si (hereinafter referred to as "a--si electrophotographic light receiving members") are generally recognized as being satisfactory in electrical optical characteristics including dark electric resistivity, photosensitivity, photoresponsibility and photoconductivity, use-environmental characteristics, durability and economical stability.
However, there is still room for the "a--si electrophotographic light receiving members to be improved in terms of total electrophotographic characteristics.
Now, along with the spread of the electrophotographic copying machine in recent years, there are increased demands for heightening the copying speed, stabilizing and improving the quality of an image reproduced.
In order to comply with these demands, there have been made improvements in the exposure mechanism, development mechanism, transfer mechanism, fixing mechanism, etc. of the electrophotographic copying machine. As a result, there is now an increased demand for a further improvement in the electrophotographic characteristics of the electrophotographic light receiving member to be used in the electrophotographic copying machine.
For instance, when image formation using the electrophotographic light receiving member is continued for a long period of time to provide a volume of copies in the electrophotographic copying machine, the cleaning blade of said machine is worn to cause a reduction in the cleaning efficiency of said blade. When this happens, it becomes impossible to obtain a high quality image unless such cleaning blade is replaced by a new one. There are disadvantages in that it takes a certain period of time for the replacement during which image formation cannot be conducted and a certain amount of expense is unavoidable for the replacement since it is done usually by a repair man.
In view of this, there is an increased demand for a further improvement not only in the cleaning blade but also in the electrophotographic light receiving member.
In order to improve the light receiving member so as to comply with the foregoing demand, there have been made proposals to use hole transporting polysilane compounds, for example, as disclosed in U.S. Pat. No. 4,618,551 or U.S. Pat. No. 4,772,525.
Each of these U.S. patents mentions a photoresponsive imaging member (namely, electrophotographic light receiving member) which has the layer constitution comprising a photoconductive layer comprised of hydrogenated amorphous silicon (hereinafter referred to as "a--Si:H") and a surface layer comprised of a hole transporting polysilane compound.
However, any of said U.S. patents does not detail about said photoconductive layer comprised of a--Si:H but simply mentions it, and does not detail about the electrophotographic characteristics of said electrophotographic light receiving member.
As for the polysilane compound used in any of the foregoing U.S. patents, it is understood that said polysilane compound is such a compound that is obtained by subjecting dichlorosilane monomer to dehydrogenation with the use of a Na catalyst to thereby synthesize a polysilane, which is presumed to be accompanied by chlorine radical on its terminal group.
Thus, it is considered that the foregoing demand can not be satisfied by any of the foregoing U.S. patents.